1. Field of the Invention
The present invention relates to ball valves and, more particularly, to a wearless top-entry ball valve assembly with a pair of camming plates coupled to the top and bottom of the ball valve member to retract the valve seats as the ball valve is rotated between open and closed positions; and, the assembly also allows for automatic flushing, i.e., flushing without removing the bonnet.
2. General Background
Current ball valves, such as disclosed in U.S. Pat. No. 4,718,444, issued to KF Industries, Inc., on application to Boelte, entitled xe2x80x9cVALVE SEAT RETRACTION METHOD AND APPARATUSxe2x80x9d do not properly seal after wear on the ball valve member and seat. The wear or damage to the seats can be in part attributed to the friction from the retraction tool as the retraction tool screws into the valve housing and retracts the seat. Repeated use of the retraction tool creates grooves and nicks in the forward end of the seat which compromises the sealing capabilities of the seat.
Additionally, I have determined that there is wear on the ball and nylon seat rings from repeated turning of the ball valve member from its open and closed position. Such wear also compromises the sealing engagement between the ball valve member and the seats.
Several other inventions related to ball valves have been patented.
For example, U.S. Pat. No. 4,262,691 issued to ACF Industries, Incorporated, of New York, N.Y., on the application of G. W. Kacal, entitled xe2x80x9cCAM MEANS FOR BALL VALVE SEAT RINGS,xe2x80x9d discloses a ball valve in which cams are mounted on the ball member to engage spring-biased seat rings and cam the seat rings to the fully retracted position at which the seat rings are retained. The seat rings are held in place while the ball member is removed for repair.
U.S. Pat. No. 3,771,545 issued to Cameron Iron Works, Inc., on the application of H. Allen, entitled xe2x80x9cBALL VALVE,xe2x80x9d discloses a ball valve including a ball closure having truncated camming surfaces and the bonnet must be removed for retraction.
U.S. Pat. No. 4,390,039 issued to Jamesbury Corporation, of Worcester, Mass., on the application of D.A. Johnson, et al., entitled xe2x80x9cVALVE ASSEMBLY AND DISASSEMBLY DEVICE,xe2x80x9d discloses a ball valve having pins to restrain the seats while the ball member is removed for repair.
Other top entry ball valves include U.S. Pat. No. 5,313,976, issued to Keystone International Holdings Corp., on application to Beasley, entitled xe2x80x9cTOP ENTRY BALL VALVE AND METHOD OF ASSEMBLYxe2x80x9d; U.S. Pat. No. 4,566,482, issued to Stunkard, entitled xe2x80x9cTOP ENTRY TRUNNION BALL VALVExe2x80x9d; U.S. Pat. No. 4,175,577, issued to ACF Industries, Inc., on application to Kacal et al., entitled xe2x80x9cMEANS AND METHOD FOR IN-LINE REMOVAL OF SEAT RINGS IN BALL VALVESxe2x80x9d; and, U.S. Pat. No. 3,037,738, issued to Jackson et al., entitled xe2x80x9cROTOR VALVExe2x80x9d none of which meet the needs of the present invention.
As will be seen more fully below, the present invention is substantially different in structure, methodology and approach from that of the known top-entry ball valve assemblies.
The preferred embodiment of top-entry ball valve assembly of the present invention solves the aforementioned problems in a straight forward and simple manner.
Broadly, the present invention contemplates a ball valve assembly comprising: a ball valve member having a stem; a pair of spring-biased valve seats adapted to be retracted; and, a pair of camming plates fixedly coupled to the top and bottom of the ball valve member about the stem and which rotate in unison with said stem, each camming plate includes a first pair of opposing camming corner-surfaces for retracting the spring-biased valve seats a first predetermined distance as the ball valve member is rotated between open and closed positions. Additionally, a second pair of opposing camming corner-surfaces are provided for full retraction of the spring-biased valve seats a second predetermined distance wherein the second predetermined distance is greater than the first predetermined distance.
The present invention contemplates a camming plate that is a quasi-rectangular or even quasi-square shaped plate with truncated corners wherein the first pair of opposing camming corner-surfaces has a first arc-length and a first radius measured from a longitudinal axis of said stem to a center of said first arc-length; and said second pair of opposing camming corner-surfaces has a second arc-length and second radius measured from said longitudinal axis of said stem to a center of said second arc-length.
In view of the above, a feature of the present invention is to provide a top-entry ball valve assembly which minimizes the wearing of the seat and ball so that the sealing engagement of the ball valve member with the seat is maintained after repeated use.
Another feature of the present invention is to provide a top-entry ball valve assembly that minimizes wearing of the seat or damage to the seat by a retraction maintaining or holding tool when the valve assembly is serviced or retraction maintaining tool used for flushing debris from between the ball and seats.
Another feature of the present invention is to provide a top-entry ball valve assembly that has seats that are not retracted from the ball under normal operating conditions.
Another feature of the present invention is to provide a top-entry ball valve assembly that allows for xe2x80x9cautomatic flushing,xe2x80x9d i.e., flushing debris from between the ball and seats without removing the bonnet and under normal operating conditions of the valve.
Another feature of the present invention is to provide a top-entry ball valve assembly that does not expose the interior of the valve during flushing of debris from between the ball and seats, unlike the devices of Boelte U.S. Pat. No. 4,718,444 and Johnson, et al., U.S. Pat. No. 4,390,039.
Another feature of the present invention is to provide a top-entry ball valve assembly in which both seats simultaneously retract under equal force (for example Johnson, et al., U.S. Pat. No. 4,390,039 has four (4) different retractors).
The above and other objects and features of the present invention will become apparent from the drawings, the description given herein, and the appended claims.